Waveguides or coaxial cables of the circular as well as elliptical kind are commonly used for feeding microwave antennas. The antennas are generally mounted on transmission towers which may extend to heights in the neighborhood of 700-800 feet. In the case of multiple feeding arrangements, a plurality of coaxial cables serving as signal transmission lines are connected to separate antennas supported on a single transmission tower and extend downwardly along the tower. At the base of the tower, the transmission lines generally extend horizontally beneath a covering waveguide bridge to shelters which house the actual transmission and/or reception apparatus. Depending upon the distance between the equipment shelters and the base of the transmission towers, the waveguide bridges themselves may be several feet long.
Under these conditions, it is imperative that each of the transmission lines or coaxial cables be rigidly anchored along its axial run extending from the shelter along the ground to the base of the tower and thereafter upward along the height of the transmission tower. In order to accomplish this, a large number of hangers is required for anchoring each cable at a plurality of positions along its axial run. Conventional arrangements for suspending coaxial cables or transmission lines from transmission towers utilize a plurality of support members disposed along the covering bridge and the transmission tower itself. The support members function as means by which a coaxial cable is anchored at different positions along its length by using some form of hangers. The hangers are generally U-shaped and each hanger is attached to its corresponding support member by a bolt extending through a hole defined in the support member and held in place by a nut and lock washer arrangement.
The process of suspending cables by using such standard hangers is fairly tedious. The hangers have to be first attached to the support members and subsequently the coaxial cable that is to be supported has to be strung along the bridge and up the tower and then clamped down between the arms of each U-shaped hanger by tightening a clamping screw which extends between the arms. The use of such hangers entails considerable installation time due to the two-step procedure involved; in addition, a substantial quantity of auxiliary hardware such as screws, bolts, nuts and washers is needed to adequately anchor the hangers.
An improved hanger which permits faster and easier attachment to a support member and a coaxial cable or waveguide and which does not require auxiliary hardware is described in co-pending U.S. patent application Ser. No. 674,558, filed Nov. 26, 1984. This earlier application is also owned by the assignee of the present application. In that application, a hanger is disclosed which can be simply snapped into an installed position on the support member and, as an incident thereto, automatically clamps the waveguide in such a manner as to securely hold the waveguide or cable without deforming and degrading it. Although the new hanger design has offered some improvement in mounting cables and waveguides on towers, further improvement is needed. For example, when more than one cable or waveguide has had to be mounted on a tower, it has been conventional practice to clamp a plurality of cable, waveguide or other transmission line runs side-by-side up and down one or more faces of the tower. It is apparent, then, that the total number of side runs which can be mounted on any give tower is limited by the widths of the tower faces. Moreover, the more runs that are placed on the faces of a tower, the less space there is available on the faces for other activities, e.g., climbing the tower for antenna installation, maintenance, etc. Additionally, the presence of the runs all around a tower increases windloading with attendant increases in design complexity, construction and maintenance of the tower.